I've had one preganat fish since I started up my tank, and I put her in a breeding trap she had the babies and al was well... until i realized that I had no where to go with the babies...oops... so I had to try and transfer then as quickly as possible to another tank, and it was all one huge freaking mess!! The idea of putting the mother in another tank until she gives birth is excellent... wish I had done that!
Also, for reference, I took an Embryology class and we raised baby zebrafish... the way we got the eggs was interesting. We put a tray of marbles in the bottom of a tank and when the fish bred (usually in the morning, it is a photoperiod related thing) the fertilized eggs fell in the marble tray and the adults couldn't get to them, and we had baby zebrafish!